Suspension for an all terrain vehicle

ABSTRACT

An all-terrain vehicle including a frame having longitudinally-spaced ends defining a first longitudinal axis, and an engine supported by the frame. The engine includes a crankshaft defining a second longitudinal axis substantially parallel to the first longitudinal axis.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 60/930,361, filed May 16, 2007, which is expressly incorporatedby reference herein.

FIELD OF THE INVENTION

The present disclosure relates to all-terrain vehicle (ATVs) having anorth/south engine orientation. Specifically, the present disclosurerelates to ATVs having an engine positioned within a frame of thevehicle in an orientation in which the crankshaft of the engine ispositioned longitudinally relative to the vehicle or perpendicular to atleast one of a front and rear axle of the ATV.

BACKGROUND AND SUMMARY

Generally, all terrain vehicles (“ATVs”) and utility vehicles (“UVs”)are used to carry one or two passengers and a small amount of cargo overa variety of terrains. Due to increasing recreational interest in ATVs,specialty ATVs, such as those used for trail riding, racing, and cargohauling have entered the market place. Most ATVs include an engineincluding between one and three cylinders. Generally, the engine ismounted in the frame of the ATV in an east/west or lateral orientationin which the crankshaft of the engine is parallel to the front or rearaxles of the ATV. Most ATVs include a straddle or saddle type seatpositioned above the engine. Depending on the engine size and the numberof cylinders, the width of the engine may become substantial, therebyrequiring a wider seat. A wider seating surface may become uncomfortablefor the rider, particularly shorter riders who may have trouble reachingthe floorboards. ATVs having east/west mounted engines may have atransmission such as a continuously variable transmission (CVT) directlycoupled to the crankshaft thereby adding additional width, or may have adifferential type mechanism transferring power to a transmission mountedelsewhere.

According to an illustrative embodiment of the present disclosure, anall-terrain vehicle includes a frame having longitudinally spaced-apartends defining a first longitudinal axis. A pair of front wheels and apair of rear wheels are operably coupled to the frame. An engine issupported by the frame and includes a plurality of cylinders and acrankshaft driven by the plurality of cylinders. The crankshaft definesa second longitudinal axis substantially parallel to the firstlongitudinal axis. A transmission is operably coupled to the engine andis configured to transmit power to a rear transmission shaft for drivingthe front wheels in motion, and to transmit power to a rear transmissionshaft for driving the rear wheels in motion. The front transmissionshaft is laterally spaced from, and extends parallel to, the reartransmission shaft.

In a further illustrative embodiment, an all-terrain vehicle includes aframe having longitudinally spaced-apart ends defining a firstlongitudinal axis. A plurality of wheels are operably coupled to theframe. An engine is supported by the frame and includes at least onecylinder and a crankshaft driven by the at least one cylinder. Thecrankshaft defines a second longitudinal axis substantially parallel tothe first longitudinal axis. The engine includes a cross-sectionalprofile configured to be received within a perimeter defining trapezoidhaving a height of approximately 432 millimeters (approximately 17inches), an upper width of approximately 229 millimeters (approximately9 inches), and a lower width of approximately 432 millimeters(approximately 17 inches).

According to another illustrative embodiment, an all-terrain vehicleincludes a frame having longitudinally spaced-apart ends defining afirst longitudinal axis. A plurality of wheels are operably coupled tothe frame. An engine is supported by the frame and includes at least onecylinder and a crankshaft driven by the at least one cylinder. Atransmission is operably coupled to the engine and is configured totransmit power to a transmission shaft for driving the wheels in motion,the transmission including a starting clutch operably coupled to, andpositioned in spaced relation to, the engine.

In yet another illustrative embodiment, an all-terrain vehicle includesa frame having longitudinally spaced-apart ends defining a firstlongitudinal axis. A plurality of wheels are operably coupled to theframe. An engine is supported by the frame and includes at least onecylinder, a crankshaft driven by the at least one cylinder, and anexhaust conduit. A transmission is operably coupled to the engine andincludes a plurality of vanes configured to force cooling air throughthe housing and across the exhaust conduit.

In a further illustrative embodiment, an all-terrain vehicle includes aframe having longitudinally spaced-apart ends defining a firstlongitudinal axis. A plurality of wheels are operably coupled to theframe. An engine is supported by the frame and is operably coupled tothe wheels. The frame includes an upper frame member having a removablemember configured to provide access to the engine.

In another illustrative embodiment, an all-terrain vehicle includes aframe including longitudinally spaced-apart ends defining a longitudinalaxis, a straddle-type seat operably coupled to the frame, a pair offront wheels operably coupled to the frame, and a pair of rear wheelsoperably coupled to the frame. A handlebar assembly is operably coupledto at least one of the wheels for steering the vehicle. An engine issupported by the frame and is operably coupled to at least one of thewheels for propelling the vehicle. A pair of footwells are laterallypositioned on opposite sides of the seat and include laterallyspaced-apart inner and outer edges, wherein the ratio of the distancebetween inner edges of the footwells and the distance between the outeredges of the footwells is less than about 0.64.

According to a further illustrative embodiment, an all terrain vehicleincludes a frame having longitudinally spaced apart ends defining afirst longitudinal axis, a pair of front wheels operably coupled to theframe, and a pair of rear wheels operably coupled to the frame. Astraddle-type seat is operably coupled to the frame, and a handlebarassembly is operably coupled to at least one of the wheels for steeringthe vehicle. An engine is supported by the frame and includes aplurality of cylinders and a crankshaft driven by the plurality ofcylinders. The crankshaft defines a second longitudinal axissubstantially parallel to the first longitudinal axis. The frame includean upper frame member having a removable member configured to provideaccess to the engine.

In a further illustrative embodiment, an all terrain vehicle includes aframe having longitudinally spaced-apart ends defining a vehiclelongitudinal axis. A pair of front wheels are operably coupled to theframe, each of the front wheels defining a front wheel center axis. Afront track width is defined laterally between the front wheel centeraxes. A pair of rear wheels are operably coupled to the frame, each ofthe rear wheels defining a rear wheel center axis. A rear track width isdefined laterally between the rear wheel center axes. An engine issupported by the frame and is operably coupled to at least one of thewheels. A front suspension includes right and left lower control arms,each lower control arm having an inner pivot coupling operably coupledto the frame and an outer pivot coupling operably to one of the frontwheels. Each lower control arm has a control arm length between theinner pivot coupling and the outer pivot coupling, the sum of thecontrol arm lengths of the right and left lower control arms defining acombined control arm length. The ratio of the combined control armlength to the front track width is at least about 0.84.

According to yet another illustrative embodiment, an all terrain vehicleincludes a frame having longitudinally spaced-apart ends defining avehicle longitudinal axis. A plurality of laterally spaced wheels areoperably coupled to the frame, each of the wheels defining a wheelcenter axis. A track width is defined laterally between the wheel centeraxes. An engine is supported by the frame and is operably coupled to atleast one of the wheels. A suspension includes right and left lowercontrol arms, each lower control arm having an inner pivot couplingoperably coupled to the frame and an outer pivot coupling operablycoupled to one of the wheels. Each lower control arm has a control armlength between the inner pivot coupling and the outer pivot coupling.Each lower control arm is angled from horizontal by less than about 30degrees and has a control arm length greater than about 423 millimeters(about 16.65 inches).

In a further illustrative embodiment, an all terrain vehicle includes aframe having longitudinally spaced-apart ends defining a vehiclelongitudinal axis. A straddle-type seat is supported by the frame. Apair of front wheels are operably coupled to the frame, each front wheelbeing rotatable about a rotational axis, and defining a front wheelcenter axis extending perpendicular to the rotational axis. A fronttrack width is defined laterally between the front wheel center axes. Apair of rear wheels are operably coupled to the frame, each rear wheeldefining a rear wheel center axis. A rear wheel track width is definedlaterally between the rear wheel center axes. An engine is supported bythe frame and is operably coupled to at least one of the wheels. A frontsuspension includes a pair of upper and lower pivot couplings operablycoupled to each front wheel, the upper and lower pivot couplingsdefining a king pin axis about which the front wheel may be rotated bysteering the vehicle. The king pin axis of each front wheel is offsetfrom the front wheel axis, as measured along the rotational axis, byless than 30 millimeters (approximately 1.18 inches).

According to still another illustrative embodiment, an all terrainvehicle includes a frame having longitudinally spaced-apart endsdefining a vehicle longitudinal axis, and a straddle-type seat supportedby the frame. A pair of laterally spaced front wheels are operablycoupled to the frame, each front wheel having an outer diameter of atleast 355 millimeters (approximately 14 inches). An inflatable tire issupported by each wheel, and a handlebar assembly is operably coupled toat least one of the wheels. An engine is supported by the frame and isoperably coupled to at least one of the wheels for propelling thevehicle. Each front wheel is operably coupled to the frame by an upperpivot coupling and a lower pivot coupling. The upper and lower pivotcouplings define a king pin axis about which the front wheel may berotated for steering the vehicle. The pivot couplings are laterallyreceived within the wheel, in a direction from the vehicle longitudinalaxis, by at least 48 millimeters (approximately 1.89 inches).

The above mentioned and other features of this invention, and the mannerof attaining them, will become more apparent and the invention itselfwill be better understood by reference to the following description ofembodiments of the invention taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ATV in accordance with illustrativeembodiments of the present invention.

FIG. 2 is a left side view of the ATV shown in FIG. 1.

FIG. 3 is a right side view of the ATV shown in FIG. 1.

FIG. 4 is a top plan view of the ATV shown in FIG. 1.

FIG. 5 is a partial top view of a middle section of the ATV shown inFIG. 1.

FIG. 6 is a bottom plan view of the ATV shown in FIG. 1.

FIG. 7 is a perspective view of the frame and suspension components ofthe ATV shown in FIG. 1.

FIG. 8 is a side view of the frame of the ATV shown in FIG. 1.

FIG. 9 is another perspective view of the frame of the ATV shown in FIG.1 with removable frame components shown in phantom.

FIG. 10A is a right side view of an engine and transmission that may beused in an ATV such as the one shown in FIG. 1.

FIG. 10B is a left side view of an engine and transmission similar toFIG. 1A.

FIG. 11 is a top view of an engine and transmission of FIGS. 10A and10B.

FIG. 12 is a cross-sectional view of the drive clutch and the drivenclutch, taken in the direction of lines 12-12 of FIG. 19B.

FIG. 13 is a perspective view of the drive clutch of FIG. 12.

FIG. 14 is a front view of an engine assembly and a trapezoidillustrating limiting dimensions of the engine assembly, in accordancewith illustrative embodiments of the present invention.

FIG. 15 is a partial perspective view of the radiator assembly of theATV shown in FIG. 1.

FIG. 16 is a partial side of the radiator of the ATV shown in FIG. 1.

FIG. 17 is a perspective view of the radiator of and cooling system ofthe ATV shown in FIG. 1.

FIG. 18A is a partially exploded front perspective view of an engine andtransmission assembly that may be used in an ATV such as the one shownin FIG. 1.

FIG. 18B is a partially exploded rear perspective view of the engine andtransmission shown in FIG. 18A.

FIG. 19A is a front perspective view of a further illustrativeembodiment transmission.

FIG. 19B is a rear perspective view of the transmission of FIG. 19A.

FIG. 19C is a rear perspective view similar to FIG. 19B, with the clutchcover and driven clutch removed from the housing and showing the driveclutch.

FIG. 20A is first rear perspective view of the internal transmissionassembly shown in FIG. 19A.

FIG. 20B is a second rear perspective view of the internal transmissionassembly shown in FIG. 20A.

FIG. 21A is a cross-sectional view of the drive clutch of FIG. 12, withthe drive clutch shown in a fully opened position.

FIG. 21B is a cross-sectional view similar to FIG. 21A, with the driveclutch shown in a static position.

FIG. 21C is a cross-sectional view similar to FIG. 21B, with the driveclutch shown in a fully closed position.

FIG. 22 is a front view of the ATV shown in FIG. 1.

FIG. 23 is a partial perspective view of the front suspension of the ATVshown in FIG. 1.

FIG. 24 is front view of the suspension components shown in FIG. 23 withthe wheels shown in cross section.

FIG. 25 is a cross-sectional view of one of the front wheels shown inFIG. 24.

FIG. 26A is a diagrammatical view of the front suspension shown in FIGS.23-25.

FIG. 26B is a diagrammatical view of the front suspension shown in FIG.26A during jounce.

FIG. 27 is an exploded view of the brake disc, hub, and fasteners shownin FIG. 23-25.

FIG. 28 is a perspective view of a lower A arm shown in FIGS. 23-25.

FIG. 29 is a rear view of the ATV shown in FIG. 1.

FIG. 30 is a partial perspective view of the rear suspension of the ATVshown in FIG. 1.

FIG. 31 is front view of the suspension components shown in FIG. 30 withthe wheels shown in cross section.

FIG. 32 is a cross-sectional view of one of the rear wheels shown inFIG. 31.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of the present invention, the drawings are not necessarilyto scale and certain features may be exaggerated in order to betterillustrate and explain the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The embodiments disclosed below are not intended to be exhaustive or tolimit the invention to the precise forms disclosed in the followingdetailed description. Rather, the embodiments are chosen and describedso that others skilled in the art may utilize their teachings. Forexample, while the following description refers primarily to an allterrain vehicle, it should be understood that the invention may haveapplication to other types of vehicles, such as snowmobiles,motorcycles, watercraft, utility vehicles, scooters, golf carts, andmopeds.

Referring initially to FIGS. 1 and 2, one illustrative embodiment of anall terrain vehicle (ATV) 10 is shown. ATV 10 includes front end 11,rear end 13, straddle-type seat 20, and handlebar assembly 26. Front end11 and rear end 13 are separated by footwells 28 on both lateral sidesof ATV 10 and separated by seat 20. Front end 11 is supported by frontwheels 12 and tires 14 and front suspension 30, which is discussed ingreater detail below. Front end 11 also includes front panel 24 whichmay include a tool storage compartment. Handlebar assembly 26 isoperably coupled to front wheels 12 to allow a rider to steer ATV 10when supported by seat 20 and/or footwells 28. Rear end 13 is supportedby rear wheels 16 and tires 18. Rear end 13 also includes rear panel 22which may include a tool storage compartment. Front panel 24 and rearpanel 22 may also include an accessory coupling system such as the onedisclosed in U.S. Pat. No. 7,055,454, the disclosure of which isexpressly incorporated by reference herein. Side panels 27 may becoupled intermediate front and rear panels 24 and 22.

In this illustrative embodiment, and as further detailed herein, frontwheels 12 and rear wheels 16 have outer diameters equal to about 355millimeters (about 14 inches). Tires 14 and 18 may be constructed to anysuitable size and pressure rating, however for the illustrativeembodiment, front tires 14 are 26×8R-14 tires (i.e., having an inflatedouter diameter of about 660 millimeters (about 26 inches) and aninflated width of about 203 millimeters (about 8 inches)), and reartires 18 are 26×10R-14 tires (i.e., having an inflated diameter of about660 millimeters (about 26 inches) and an inflated width of about 254millimeters (about 10 inches)). Both front tires 14 and rear tires 18are low pressure tires, illustratively operated at a maximum airpressure of about 7 pounds per square inch (about 0.5 Kg/CM²). For theillustrative embodiment, tires 14 and 18 provide a significant amount ofsuspension for ATV 10. Front tires 14 extend forward of forwardmostcomponents of ATV 10, illustratively front panel 24, and may act as afront “bumper” for ATV 10. As such, front tires 14 are configured toprevent damage to ATV 10 or a transporting vehicle, especially if ATV 10is transported in a pickup truck bed or similar vehicle.

Referring now to FIG. 3, shift lever 23 is shown on the right side ofATV 10. Shift lever 23 is coupled to a transmission of ATV, which isdescribed in greater detail below. Distance 32 is ground clearance ofATV 10. In this illustrative embodiment, distance 32 is equal to about305 millimeters (about 12 inches). FIGS. 4 and 5 illustrate a top viewof ATV 10. Distance 36 is the overall width of ATV 10. In thisillustrative embodiment, distance 36 is defined to be less than 1219millimeters (approximately 48 inches), and is illustratively equal toabout 1206.5 millimeters (about 47.5 inches). Distance 34 is equal tothe width of footwells 28 on both lateral sides of ATV 10. In thisillustrative embodiment, distance 34 is about 330 millimeters (about 13inches) measured as from proximate center portion sidewall 33 to outeredge 35 of each respective footwell 28. Referring to FIG. 5, distance 44is equal to the width of ATV 10 between inner edges 33 of footwells 28.In this illustrative embodiment, distance 44 is about 421.6 millimeters(about 16.6 inches). As may be appreciated, the ratio of the lateraldistance between inner edges 33 of footwells 28 and the lateral distancebetween the outer edges 35 of footwells 28 is equal to approximately0.64, and is illustratively less in order to provide a narrower straddlewidth 44 for the rider. Distance 44, as measured between sidewalls 33,is the distance a rider positioned on seat 20 will straddle. It may bepreferable for a rider to straddle seat 20 in the seated position withboth feet resting in footwells 28. Footwells 28 include traction devices38 to contact a rider's footwear. Additionally, right footwell 28includes foot brake lever 42. A rider may apply one of a hand brakelever 43 on handlebar assembly 26 and foot brake lever 42 to applyeither a front brake assembly, a rear brake assembly, or both.

Referring now to FIGS. 6-8, ATV 10 includes frame 50 defining alongitudinal axis 51 and which includes front portion 52, middle portion54, and rear portion 56. Frame 50 is shown with the engine 72 andtransmission 74, as further detailed herein, removed for simplicity. Asshown in FIG. 8, front portion 52 and rear portion 54 of frame 50 areangled upwardly to provide additional ground clearance to front end 11and rear end 13 of ATV 10. Front portion 52 is angled upwardly at anangle defined by reference numeral 58 relative to middle portion 54.Rear portion 56 is angled upwardly at an angle defined by referencenumeral 60 relative to middle portion 54. Middle portion 54 extendsgenerally horizontal between front portion 52 and rear portion 56. Inthe illustrative embodiment, angles 58 and 60 are defined to be within arange from about 8.5 to 9.5 degrees.

Referring now to FIGS. 7 and 9, frame 50 includes removable framemembers 62 and 66. Removable frame member 62 forms a portion of upperframe tube 64 in its default or fixed position. A plurality offasteners, such as bolts 67, are used on each end of removable framemember 62 to couple it to upper frame tube 64 ( FIG. 9). Removable framemember 62 may be removed by the rider or a technician to service theengine 72 or other components of ATV 10. Similarly, removable framemember 66 forms a portion of down tube 68 in its default or fixedposition. A plurality of fasteners, such as bolts 69, are used on eachend of removable frame member 66 to couple it to down tube 68. Removablemember 66 may be removed to service various internal components of ATV10 such as the CVT belt 155, which is explained in greater below.

FIGS. 10A-11 are illustrative side and top views of engine 72 andtransmission 74 of ATV 10. Engine 72 is positioned adjacent front end 11of ATV 10. Transmission 74 is illustratively coupled directly to engine72 in the manner detailed herein. Transmission 74 provides power tofront differential 80 through front transmission shaft 81 and to reardifferential 78 through rear transmission shaft 83. Front differential80 powers front axle 116. Rear differential 78 powers rear axle 118. Inthis illustrative embodiment, transmission 74 also includes housing 90and clutch cover 92. Clutch cover 92 includes an outer wall of varyingdepth that cooperates with flange 94 of housing 90. The inwardly curvedshape of flange 94 and corresponding shape of clutch cover 92facilitates removal of clutch cover 92 for service when removable framemember 66 is removed. More particularly, the shape of the clutch cover92 does not require that left rear wheel 16 be removed for certainservicing of the transmission 74. Furthermore, no air ducts are coupleddirectly to the clutch cover 92, thereby further facilitating ease ofremoval and replacement. Clutch cover 92 may be coupled to flange 94 ofhousing 90 by any suitable fastening means, such as conventional nutsand bolts or machine screws 113 (FIGS. 19A and 19B). While outer wall ofclutch cover 92 and flange 94 are shown as having curved shapes, itshould be appreciated that any inwardly angled surface may besubstituted therefore.

Engine 72 includes removable fuel tank 82 and air intake 84. Muffler 76is coupled to engine 72 by exhaust conduit 75. In this illustrativeembodiment, engine 72 in an inline 2 cylinder engine having adisplacement of 850 cubic centimeters, although any suitable engine maybe used. Engine 72 is hard mounted to frame 50 and oriented in anorth/south or longitudinal position. More particularly, the crankshaft73 (FIGS. 17 and 18) of engine 72 defines a longitudinal axis 71 whichis substantially parallel to frame longitudinal axis 51, and isperpendicular to front axle 116 and rear axle 118.

In the illustrative embodiment of FIGS. 10A-11, an updraft system 85provides air flow passages from the air intake 84 to the cylinder ports89 a and 89 b (FIG. 10A) of engine 82 in a manner facilitating a narrowwidth of the upper portion of engine 82. As noted herein, such narrowwidth of engine 82 provides a comfortable riding position for thedriver. Air intake 84 is in fluid communication with an updraft intakemanifold 91, which defines a chamber below runners 93. Air, representedby arrows 95 in FIG. 10A, flows from air intake 84 through conduit 96and into manifold 91. Air 95 then flows upwardly from manifold 91 (i.e.,updraft) through runners 93A and 93B into cylinder ports 89A and 89B,respectively. A throttle body 97 is illustratively attached to manifold91, and may be coupled at either end or centered with respect tomanifold 91 in order to assist in tuning and in facilitating the flow ofair 95 to engine 82. In an alternative arrangement, separate throttlebodies 97 may be used for each cylinder, and mounted below the intakerunners 93 and coupled thereto for each cylinder. Such an arrangementpermits the ergonomic narrow package at the upper portion of engine 82,while changing the flow and tuning characteristics of the intake chamberof manifold 91.

Referring now to FIGS. 10A-12, in this illustrative embodiment,transmission 74 is a CVT (Continuously Variable Transmission), sometimesreferred to as a variable pulley transmission. Transmission 74 includesa primary variable pulley or drive clutch 98 and a secondary variablepulley or driven clutch 99. With reference to FIGS. 12, 13, and 19C, anillustrative example of primary variable pulley or drive clutch 98received within housing 90 and clutch cover 92 is shown. Drive clutch 98is mounted to a rotatable input shaft 101 and includes a movable pulleymember or sheave 100 and a stationary pulley member or sheave 102. Aclutch mechanism 106 is operably coupled to movable sheave 100 and isconfigured to control movement of the movable sheave along the shaft 101closer to and further away from stationary sheave 102.

With reference to FIG. 12, driven clutch 99 is mounted to a rotatableoutput shaft 103, and is illustratively coupled to additional drivetrain components as further detailed below. Driven clutch 99 may be ofconventional design as including a movable pulley member or sheave 105and a stationary pulley member or sheave 108. A clutch mechanism 111 isconfigured to normally urge movable sheave 105 toward stationary sheave108. A generally V-shaped belt 155 extends between the drive clutch 98and the driven clutch 99. Additional details of continuously variabletransmissions are provided in U.S. Pat. Nos. 6,149,540 and 7,163,477,the disclosures of which are expressly incorporated by reference herein.

With further reference to drive clutch 98 of FIGS. 10A-13, stationarypulley plate 102 includes a plurality of fins or vanes 104 in animpeller shaped orientation. When engine 72 provides power totransmission 74, input shaft 101 rotates outer pulley plate 102. Vanes104 create air movement and pump cooling air through transmission 74.More particularly, air flow (shown by arrows 107) is received fromconduit 86 and enters housing 90 (FIG. 10A). The cooling air 107 isforced by vanes 104 through housing 90 and out though an opening inhousing 90 to conduit 88 (FIG. 10B). Conduit 88 is fluidly coupled tovent 87 that is positioned adjacent to exhaust conduit 75. The heatedair from transmission 74 exits vent 87 and cools exhaust conduit 75 toreduce heat radiated from the exhaust to body panels 22 and 27. Theheated air from transmission 74 is substantially cooler than exhaustconduit 75 and provides a significant cooling effect. In an alternativeembodiment, air flow supplied to vent 87 may be provided by an elementcontrolled separately from transmission 74, such as an electric fan thatmay be used on demand.

FIG. 14 is an illustrative cross-sectional view of engine 72 shownwithin a perimeter defining trapezoid 109. In this illustrativeembodiment, engine 72 has been designed to fit within limits of an outerperimeter defined by trapezoid 109. Trapezoid 109 is defined by height112, upper width 110, and lower width 114. Illustratively, height 112 iswithin a range of 279 millimeters (about 11 inches) to 518 millimeters(about 20.39 inches), upper width 110 is within a range of 148millimeters (about 5.83 inches) to 275 millimeters (about 10.38 inches),and lower width 114 is within a range of 279 millimeters (about 11inches) to 518 millimeters (about 20.39 inches). For this exemplaryembodiment, height 112 is equal to about 432 millimeters (about 17inches), upper width 110 is equal to about 229 millimeters (about 9inches), and lower width 114 is equal to about 432 millimeters (about 17inches). Trapezoid 109 defines the approximate shape and size a rider ofATV may straddle to be comfortably seated on seat 20 of ATV 10. Reducingthe upper and lower widths 110 and 114 of trapezoid 109 may improverider comfort, especially shorter riders who may have trouble straddlingseat 20 and contacting footwells 28.

Referring now to FIGS. 15-17, front end 11 of ATV 10 is shown asincluding radiator 117. Front end 11 of ATV 10 also includes frontportion 115 of frame 50. Radiator 117 is coupled to engine 72 and coolsthe engine coolant from engine 72. Cooling fan 120 is positioned behindradiator 117 to draw cooling air over radiator 117 (FIGS. 15 and 16).Cooling fan 120 may be powered by any suitable means such as an electricor hydraulic motor, or directly off of engine 72. Coolant overflowbottle 122 is also coupled to radiator 117. As shown best in FIG. 15,radiator 117 is tilted backward relative to a vertical axis at an angledesignated by reference numeral 120. In this illustrative embodiment,angle 121 is equal to about 24 degrees. Tilting radiator 117 back allowsradiator 117 to have a larger cooling surface area than if it wereoriented vertically. For example, the surface area of radiator 117 maybe approximately 1155 square centimeters (approximately 179 squareinches) compared to approximately 1061 square centimeters (approximately164.5 square inches) if radiator 117 were oriented vertically. Moreparticularly, the illustrative embodiment angled radiator 117 hasdimensions of approximately 393 millimeters (approximately 15.5 inches)by approximately 294 millimeters (approximately 11.6 inches). A radiatororiented in a vertical plane and sized to fit within the same packagewould have dimensions of approximately 393 millimeters (approximately15.5 inches) by approximately 270 millimeters (approximately 10.6inches).

Referring now to FIGS. 18A and 18B, engine 72 and transmission housing124 are shown. Engine 72 includes flywheel 128 which is driven off thecrankshaft 73 (shown in phantom in FIGS. 17A and 17B) of engine 72.Starter 126 may be used to rotate flywheel 128 when engine 72 isstarted. Flywheel 128 includes coupler 130 which cooperates withrotational member 132 of transmission housing 124. Rotational member 132is coupled to one end of shaft 134 and transmits power from flywheel 128to shaft 134. More particularly, coupler 130 is a female component whichreceives rotational member 132, a male component, in a rotationallyfixed relationship. Coupler 130 is illustratively made of a resilientmaterial, such as elastomeric rubber, and provides torsional dampeningbetween engine 72 and transmission 74. More particularly, coupler 130reduces gear noise, reduces torque pulses, and reduces impact loading ofgear teeth.

A further illustrative transmission 74′ is shown in FIGS. 19A-20B foruse with a different sized engine (not shown). Transmission 74′ issubstantially similar to transmission 74 and, as such, like componentsare identified with like reference numbers.

With further reference to FIGS. 20A and 20B, a starting clutch 150 iscoupled to shaft 134. Shaft 135 and gear 152 extend from starting clutch150. Starting clutch 150 may be calibrated to engage when shaft 135reaches any suitable revolutions per minute (RPMs). When thepredetermined RPM of shaft 134 is reached, starting clutch 150 rotatesshaft 135 and gear 152. Starting clutch 150 may illustratively compriseany conventional centrifugally activated starting clutch positionedwithin transmission housing 124.

With further reference to FIGS. 12, 20A and 20B, rotation of gear 152rotates gear 148 and shaft 146. Input shaft 101 of drive clutch 98 (FIG.12) is coupled to the shaft 146. Output shaft 154 of driven clutch 99(FIG. 12) is coupled to shaft 154. Belt 155 extends between thesevariable pulleys 98 and 99 to transfer rotational power from the drivepulley 98 coupled to shaft 146 to the driven pulley 99 coupled to shaft154, in a known manner. In this embodiment, the drive and drivenclutches 98 and 99 rotate in an opposite direction relative to thecrankshaft 73 of engine 72 to produce a counterbalancing effect thatreduces overall gyro or rotational forces of engine 72 and transmission74 on frame 50, thereby facilitating hard mounting of engine 72 to frame50. More particularly, opposing rotational forces offset each other,thereby reducing rotation about the vehicle's roll axis (about theengine crankshaft 73). In other words, vehicle rotational (gyro) effectis reduced by opposing moments of rotation between engine 72 andtransmission 74.

With reference to FIGS. 12 and 21A-21C, additional details ofillustrative drive clutch 98 are shown. Clutch mechanism 106 of driveclutch 98 includes a first or primary spring 161 for normally biasingmovable sheave 100 away from stationary sheave 102. Clutch mechanism 106also includes a plurality of pivotally mounted centrifugal weights 163which urge movable sheave 100 toward stationary sheave 102 in responseto rotation of drive clutch 98. Thus, drive belt 155 rides near thecenter of drive clutch 98 when the engine 72 (and, hence, the driveclutch 98) is rotating at slow speeds. At higher speeds, the centrifugalweights 163 urge movable sheave 100 toward stationary sheave 102,thereby pinching belt 155 and causing it to move outwardly betweensheaves 100 and 102.

A spider 164 is secured for rotation with input shaft 101, and iscaptured between movable sheave 100 and a cover 165 which, in turn, issecured to movable sheave 100. First spring 161 urges cover 165 and,therefore, movable sheave 100 away from stationary sheave 102. Radiallyextending ends of spider 164 provide bearing surfaces 166 against whichcentrifugal weights 163 act to urge movable sheave 100 toward stationarysheave 102 at rotational speeds above engine idle.

A second or pre-load spring 167 is received intermediate spider 164 andmovable sheave 100. Second spring 167 is configured to bias movablesheave 100 toward stationary sheave 102 with sufficient force to pinchbelt 155 when there is little or no rotation of drive clutch 98 (i.e.,when the centrifugal weights 163 are not urging movable sheave 100toward stationary sheave 102 with more than a nominal force). Secondspring 167 also helps keep belt 155 tight within sheaves 100 and 102,thereby reducing logging or slippage. Second spring 167 furthercompensates for belt wear by helping the belt maintain its relativeposition within sheaves 100 and 102, thereby preserving the transmissionratio between clutches 98 and 99.

FIGS. 21A-21C illustrate three different positions of drive clutch 98,corresponding to three different speeds of transmission 74. FIG. 21Ashows drive clutch 98 in a fully open position. This open positionoccurs when tension within belt 155 is sufficient to overcome the biasof second spring 167, typically due to torque feedback from drivenclutch 99.

FIG. 21B shows drive clutch 98 in a static or partially closed position.This static position occurs when rotation of the flyweights 163 hasurged movable sheave 100 toward stationary sheave 102. Secondary spring167 applies a side force on belt 155. In this position the load of thefirst spring 161 is substantially equal to the load of the second spring167 (without belt 155). If the vehicle were to stop suddenly, driveclutch 98 would only open to this position, and belt 155 would remain incontact with sheaves 100 and 102.

FIG. 21C shows drive clutch 98 in a fully closed position. In such aposition, second spring 167 has exceeded its free length. As such,second spring 167 is no longer applying force against movable sheave100.

Drive clutch 99 is configured to operate at optimum rotational speed(RPM) regardless of the type of engine 72 used. More particularly,transmission 74 is configured to facilitate the changing of gears 148and 152 such that clutches 98 and 99, respectively, operate at efficientrotational speeds for different engines 72 that may be coupled to thetransmission 74. This allows the transmission 74 to be adaptable to awide variety of engines 72.

As shown in FIGS. 12, 20A, and 20B, when driven clutch 99 on shaft 154rotates, gear 156 on shaft 154 rotates gear 158 on shaft 159. Shaft 159also includes sprocket 160 which rotates belt or chain 162. Belt 162rotates sprocket 141 on shaft 136. Shaft 136 includes splined portion137 which transfers power to rear differential 78. Shaft 136 alsorotates gear 142 which, in turn, rotates gear 140 on shaft 138. Shaft138 includes splined portion 139 which transfers power to frontdifferential 80. In this illustrative embodiment, gears 142 and 140 havedifferent diameters to rotate shafts 136 and 138 at different speeds. Itshould be noted that although gears 156 and 158 are shown in cavity 144in housing 124, any suitable gear set may be positioned in cavity 144.Such gear sets may include multiple forward speeds and/or a reverse gearthat may be actuated by a shift lever, such as shift lever 23 as shownin FIG. 3. It should be appreciated that the longitudinal orientation ofshafts 134, 146, 154, 159, 136, and 138 facilitates the addition andsubstitution of gear reductions and step-ups within the drivelinedefined by engine 72 and transmission 74, without affection dimension 44of rider straddle width (FIG. 5).

Referring now to FIGS. 22-25, front end 11 and front suspension 30 ofATV 10 are shown. Front suspension 30 includes upper and lower controlarms, illustratively A arms 172 and 170, on each side of ATV 10. Upper Aarms 172 are coupled on one end at upper inner pivot couplings 187 tobrackets 188 of tube 186 of front portion 52 of frame 50. On theopposing ends, upper A arms 172 are coupled at upper outer pivotcouplings 194, illustratively ball joints, to spindles 190. Lower A arms170 are coupled on one end at lower inner pivot couplings 189 tobrackets 184 of front portion 52 of frame 50. On the opposing ends,lower A arms 170 are coupled at lower outer pivot couplings 196,illustratively ball joints, to spindles 190. Upper A arms 172 alsoinclude brackets 182 which are coupled to shock absorbers 180. Shockabsorbers 180 dampen the upward and downward travel of frame 50 relativeto spindles 190, and thus wheels 12, to provide a comfortable ride tothe rider of ATV 10. A wheel hub 174 is supported for rotation relativeto each spindle 190 about rotational axis 191, in a known manner. Aplurality of fasteners 198 cooperating with lug nuts 207 couple wheel 12to hub 174.

Front axles or half shafts 116 extend from front differential 80 throughspindles 190 on each lateral side of front end 11 of ATV 10. Each halfshaft 116 is operably coupled to a respective hub 174 and thus wheel 12.In this illustrative embodiment, ATV 10 is four-wheel drive. As such,front axles 116 are rotated by front differential 80 to power frontwheels 12, and rear axles 118 are rotated by rear differential 78 topower rear wheels 16.

Referring further to FIGS. 22 and 23, cross-sectional views for frontwheels 12 and tires 14 are shown. As shown in FIG. 23, properly inflatedtires 14 define width 192, while wheels 12 define width 193. In thisillustrative embodiment, width 192 is equal to approximately 203millimeters (approximately 8 inches), while width 193 is equal toapproximately 173 millimeters (approximately 6.8 inches). Wheels 12 areconfigured such that spindle 190 is positioned within width 193. In thisconfiguration, upper and lower A arms 172 and 170 extend into width 193of wheels 12 to couple to ball joints 194 and 196, respectively. In theillustrative embodiment, upper ball joint 194 is laterally recessedwithin wheel 12 by approximately 48.3 millimeters (approximately 1.9inches). This allows upper and lower A arms 172 and 170 to have asubstantially longer length than if spindles 190 extended outside ofwidth 193 of wheels 12. Increasing the length of upper and lower A arms172 and 170 may reduce the travel angles of axles 116 during jounce inaddition to increasing the length of travel of wheels 12 during jounce.An example of jounce is shown diagrammatically in FIG. 24B. Jounceoccurs when at least one of front wheels 12 encounters a bump.

With further reference to FIG. 25, upper and lower ball joints 194 and196 together define an axis of rotation, commonly referred to as a kingpin axis 195. Turning of the handlebar assembly 26 results in rotationof the front wheel 12 about the king pin axis 195. Each front wheel 12and tire 14 defines a front wheel center axis 197. A king pin offset 199is defined as the distance between the king pin axis 195 and the wheelcenter axis 197, as measured along the rotational axis 191. The improvedride and handling characteristics detailed above are realized byreducing the king pin offset 199. In the illustrative embodiment, theking pin offset 199 is less than about 30 millimeters (about 1.18inches), and is illustratively equal to about 28.5 millimeters (about1.12 inches).

Referring to FIG. 26A, a front track width 204 is defined as the lateraldistance between the right and left front wheel center axes 197 a and197 b. In the illustrative embodiment, front track width 204 is betweenabout 474 millimeters (about 18.66 inches) and 523 millimeters (about20.59 inches). In order to facilitate the aforementioned ride andhandling characteristics, a high ratio of lower A arm length 205 totrack width 204 is desired. In the illustrative embodiment, the length205 of each lower A arm 170 (between inner and outer pivot couplings 189and 196) is about 440 millimeters (about 17.32 inches). As such, theratio of A arm length 205 to track width 204 is illustratively betweenabout 0.84 and 0.93.

Referring to FIGS. 25 and 27, and as noted above, spindle 190 is coupledto hub 174. Hub 174 includes plurality of apertures 200 and internalsplined portion 173. Internal splined portion 173 receives one of frontaxles 116. Brake disc 176 has an outer band 177 and mounting extensions179 having apertures 181. The brake disc 176, as shown in FIG. 27 isdefined with an inner opening of cruciform shape. Brake disc 176 iscoupled to hub 174 by fasteners 198 which extend through apertures 181and 200. Serrated or splined portions 206 of fasteners 198 are press fitinto frictional engagement with hub 174. Lug nuts 207 are threadablyreceived on a threaded portion 208 of each fastener 198 and engage wheel12. As such, fasteners 198 act as wheel studs and couple together all ofbrake disc 176, hub 174, and wheel 12. By fasteners 198 securing brakedisc 176 in addition to wheel 12, strength is increased by distributingthe load, while reducing cost, weight, part count, and brake noise. In aknown manner, brake caliper 178 may be actuated to grip or squeeze brakedisc 176 when slowing or stopping ATV 10. Larger (i.e. 14 inch) wheels12 facilitate the use of greater diameter brake discs 176, therebyproviding a larger surface for engagement by the brake caliper 178 andimproving braking efficiency. In the illustrative embodiment, each brakedisc 176 has an outer diameter of approximately 240 millimeters(approximately 9.45 inches). Also as shown best in FIG. 23, the brakecaliper is mounted over an upper right hand quadrant of the brake discas viewed from the outside.

Referring now to FIG. 28, an exemplary embodiment of lower A arm 170 isshown. For this illustrative embodiment of ATV 10, lower A arm 170 isformed by tubes 201. Tubes 201 include ends 202 which may be used tocouple lower A arm 170 to a portion of ball joint 196. Ends 202 are“crushed” or “squeezed” to provide a flat portion to form apertures 203.Crushed ends similar to ends 202 of lower A arm 170 may be used anyother suitable tube formed structure of ATV such as frame 50 and upper Aarms 172.

Referring now to FIGS. 29-32, rear suspension 210 of ATV 10 is shown.Rear suspension 210 includes upper and lower control arms,illustratively A arms 220 and 218, on each lateral side of rear end 13of ATV 10. Upper and lower A arms 220 and 218 couple spindles 216 torear portion 56 of frame 50. Upper A arms 220 are coupled on one end atupper inner pivot couplings 221 to upper rear frame bracket 224 (FIG.31). Upper rear frame bracket 224 is also coupled to torsion support 223which supports torsion bar 226. On the opposing end, upper A arms 220are coupled at upper outer pivot couplings 227 to spindles 216.Similarly, lower A arms 218 are coupled on one end at lower inner pivotcouplings 229 to lower rear frame bracket 222, and to spindles 216 atlower outer pivot couplings 231 on the opposing end.

Rear axles or half shafts 118 extend from rear differential 78 to hubs216 to power rear wheels 16 of ATV 10. Rear axles 118 are positionedbetween upper and lower A arms 220 and 218. Shock absorbers 230 arecoupled between upper bracket 233 of frame 50 and brackets 217 of lowerA arms 218. Shock absorbers 230 extend through an opening of in upper Aarms 220 to couple to brackets 217 of lower A arms 218. In operation,shock absorbers 230 dampen the upward and downward movement of frame 50relative to spindles 216, and thus wheels 16, through the range ofmotion of upper and lower A arms 220 and 218 during jounce.

Referring further to FIG. 30, a cross-sectional view of one of rearwheels 16 and tires 18 is shown. The orientation of spindles 216 withinrear wheels 16 is similar to the orientation of spindles 190 in frontwheels 12, discussed above. Properly inflated rear tires 18 define width234, while rear wheels 16 define width 235. In this illustrativeembodiment, width 234 is equal to approximately 279 millimeters(approximately 11 inches), while width 235 is equal to approximately223.5 millimeters (approximately 8.8 inches). Spindles 216 arepositioned in the respective interior cavities of rear wheels 16.Spindles 216 and a portion of upper and lower A arms 220 and 218 arelaterally positioned within width 235 of rear wheels 16. As discussedabove, this orientation allows upper and lower A arms 220 and 218 to belonger than those in a system in which the spindles 216 are not fullyenclosed within the width of the wheel 16. Longer A arms 220 and 218 maylead to a greater range of motion of rear wheels 16 and reduce the angleof rear axles 118 coupling with spindles 216 relative to horizontal.

Referring further to FIG. 31, rear wheel 16 and tire 18 define a rearwheel center axis 236. A rear track width 238 is defined as the lateraldistance between the right and left rear wheel center axes 236 a and 236b. In the illustrative embodiment, rear track width 238 is between about455 millimeters (about 17.91 inches) and 502 millimeters (about 19.76inches). In the illustrative embodiment, the length 240 of each lower Aarm 218 (between pivot couplings 229 and 231) is about 424 millimeters(about 16.69 inches). As such, the ratio of A arm length 240 to trackwidth 238 is illustratively between about 0.84 and 0.93.

With further reference to FIGS. 30 and 42, spindles 216 are coupled tohubs 212 which are similar to hubs 174 (FIGS. 25 and 27). Brake disc 214is coupled to hub 212 by fasteners 198. Rear wheels 16 are coupled tohubs 212 by lug nuts 207 engaging fasteners 198. Brake discs 214 aresqueezed by brake calipers 239 when a brake of ATV 10 is actuated andmay be of a similar design as brake discs 176 detailed above.

Front suspension 30 and rear suspension 210 may include certain elementsof the Predator™ brand ATV and the Outlaw™ brand ATV, both availablefrom Polaris Industries, the assignee of the present disclosure. Detailsof the Predator™ brand ATV suspension are disclosed in U.S. Pat. Nos.6,767,022, 7,000,931, and 7,004,484, the disclosures of which areexpressly incorporated by reference herein. Details of the Outlaw™ brandATV suspension are disclosed in U.S. patent application Ser. No.11/528,889, filed Sep. 27, 2006, and U.S. patent application Ser. No.11/543,430, filed Oct. 5, 2006, both of which claim the benefit of U.S.Ser. No. 60/813,597, filed Feb. 1, 2006, the disclosures of which areexpressly incorporated by reference herein.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

1. An all-terrain vehicle including: a frame including longitudinallyspaced-apart ends defining a vehicle longitudinal axis; a pair of frontwheels operably coupled to the frame, each of the front wheels defininga front wheel center axis, a front track width being defined laterallybetween the front wheel center axes and each front wheel rotates about arotational axis; a pair of rear wheels operably coupled to the frame,each of the rear wheels defining a rear wheel center axis, a rear trackwidth being defined laterally between the rear wheel center axes; anengine supported by the frame and operably coupled to at least one ofthe wheels; a front suspension including right and left lower controlarms, each lower control arm having an inner pivot coupling operablycoupled to the frame and an outer pivot coupling operably coupled to oneof the front wheels, each lower control arm having a control arm lengthbetween the inner pivot coupling and the outer pivot coupling, the sumof the control arm lengths of the right and left lower control armsdefining a combined control arm length; the front suspension furtherincludes right and left upper control arms, each upper control armhaving an inner pivot coupling operably coupled to the frame and anouter pivot coupling operably coupled to one of the front wheels; andwherein the ratio of the combined control arm length to the front trackwidth is at least about 0.84 and the outer pivot couplings of each pairof upper and lower control arms define a king pin axis offset from thefront wheel axis, measured along the rotational axis, by less than 30millimeters.
 2. The all-terrain vehicle of claim 1, wherein the engineincludes a plurality of cylinders and a crankshaft driven by theplurality of cylinders, the crankshaft extending substantially parallelto the vehicle longitudinal axis.
 3. The all-terrain vehicle of claim 1,wherein the ratio of the combined control arm length to the track widthis defined to be between about 0.84 to about 0.93.
 4. The all-terrainvehicle of claim 1, wherein the track width is defined to be betweenabout 948 millimeters to about 1046 millimeters.
 5. The all-terrainvehicle of claim 1, wherein the control arm length is substantiallyequal to 440 millimeters.
 6. The all-terrain vehicle of claim 1, whereineach control arm is angled from horizontal by less than about 30degrees.
 7. The all-terrain vehicle of claim 1, further comprising: arear suspension including right and left lower control arms, each lowercontrol arm having an inner pivot coupling operably coupled to the frameand an outer pivot coupling operably coupled to one of the front wheels,each lower control arm having a control arm length between the innerpivot coupling and the outer pivot coupling, the sum of the control armlengths of the right and left lower control arms defining a combinedcontrol arm length; and wherein the ratio of the combined control armlength to the rear track width is at least about 0.84.
 8. Theall-terrain vehicle of claim 7, wherein the ratio of the combinedcontrol arm length of the rear suspension to the rear track width isdefined to be between about 0.84 to about 0.93.
 9. The all-terrainvehicle of claim 7, wherein the rear track width is defined to bebetween about 910 millimeters to about 1004 millimeters.
 10. Theall-terrain vehicle of claim 7, wherein the control arm length issubstantially equal to 424 millimeters.
 11. An all-terrain vehicleincluding: a frame including longitudinally spaced-apart ends defining avehicle longitudinal axis; a plurality of laterally spaced wheelsoperably coupled to the frame, each of the wheels defining a wheelcenter axis, a track width being defined laterally between the wheelcenter axes; an engine supported by the frame and operably coupled to atleast one of the wheels; a suspension including right and left lowercontrol arms, each lower control arm having an inner pivot couplingoperably coupled to the frame and an outer pivot coupling operablycoupled to one of the wheels, each lower control arm having a controlarm length between the inner pivot coupling and the outer pivotcoupling; and wherein each lower control arm is angled from horizontalby less than about 30 degrees and has a control arm length greater thanabout 423 millimeters, and wherein each lower control arm has a controlarm length between the inner pivot coupling and the outer pivotcoupling, the sum of the control arm lengths of the right and left lowercontrol arms defining a combined control arm length where the ratio ofthe combined control arm length to the track width is at least about0.84.
 12. The all-terrain vehicle of claim 11, wherein the ratio of thecombined control arm length to the track width is defined to be betweenabout 0.84 to about 0.93.
 13. The all-terrain vehicle of claim 11,wherein the track width is defined to be between about 910 millimetersto about 1046 millimeters.
 14. The all-terrain vehicle of claim 11,wherein the control arm length is between about 423 millimeters andabout 440 millimeters.
 15. The all-terrain vehicle of claim 11, wherein:each front wheel rotates about a rotational axis; the front suspensionfurther includes right and left upper control arms, each upper controlarm having an inner pivot coupling operably coupled to the frame and anouter pivot coupling operably coupled to one of the front wheels; andthe outer pivot couplings of each pair of upper and lower control armsdefine a king pin axis offset from the front wheel axis, measured alongthe rotational axis, by less than 30 millimeters.
 16. An all-terrainvehicle including: a frame including longitudinally spaced-apart endsdefining a vehicle longitudinal axis; a straddle-type seat supported bythe frame; a pair of front wheels operably coupled to the frame, eachfront wheel rotatable about a rotational axis, and defining a frontwheel center axis extending perpendicular to the rotational axis, afront track width being defined laterally between the front wheel centeraxes; a pair of rear wheels operably coupled to the frame, each rearwheel defining a rear wheel center axis, a rear track width beingdefined laterally between the rear wheel center axes; an enginesupported by the frame and operably coupled to at least one of thewheels; a front suspension including a pair of upper and lower pivotcouplings operably coupled to each front wheel, the upper and lowerpivot couplings defining a king pin axis about which the front wheel maybe rotated for steering the vehicle; and wherein the king pin axis ofeach front wheel is offset from the front wheel axis, as measured alongthe rotational axis, by less than 30 millimeters.
 17. The all-terrainvehicle of claim 16, wherein: the front suspension includes right andleft lower control arms, each lower control arm having an inner pivotcoupling operably coupled to the frame and an outer pivot couplingoperably coupled to one of the front wheels, each lower control armhaving a control arm length between the inner pivot coupling and theouter pivot coupling, the sum of the control arm lengths of the rightand left lower control arms defining a combined control arm length; andwherein the ratio of the combined control arm length to the track widthis at least about 0.84.
 18. The all-terrain vehicle of claim 17, whereinthe track width is defined to be between about 948 millimeters to about1046 millimeters.
 19. The all-terrain vehicle of claim 18, wherein thecontrol arm length is substantially equal to 440 millimeters.
 20. Theall-terrain vehicle of claim 17, wherein each of the control arms isangled from horizontal by less than about 30 degrees.
 21. Theall-terrain vehicle of claim 17, further comprising: a rear suspensionincluding right and left lower control arms, each lower control armhaving an inner pivot coupling operably coupled to the frame and anouter pivot coupling operably coupled to one of the front wheels, eachlower control arm having a control arm length between the inner pivotcoupling and the outer pivot coupling, the sum of the control armlengths of the right and left lower control arms defining a combinedcontrol arm length; and wherein the ratio of the combined control armlength to the rear track width is at least about 0.84.
 22. Theall-terrain vehicle of claim 21, wherein the rear track width is definedto be between about 910 millimeters to about 1004 millimeters.
 23. Theall-terrain vehicle of claim 22, wherein the control arm length issubstantially equal to 424 millimeters.
 24. An all-terrain vehiclecomprising: a frame including longitudinally spaced-apart ends defininga vehicle longitudinal axis; a straddle-type seat supported by theframe; a pair of laterally spaced front wheels operably coupled to theframe, each front wheel having an outer diameter of at least about 355millimeters; an inflatable tire supported by each wheel; a handlebarassembly operably coupled to at least one of the wheels; an enginesupported by the frame and operably coupled to at least one of thewheels for propelling the vehicle; each front wheel being operablycoupled to the frame by an upper pivot coupling and a lower pivotcoupling, the upper and lower pivot couplings defining a king pin axisabout which the front wheel may be rotated for steering the vehicle; andwherein the pivot couplings are laterally received within the wheel, ina direction from the vehicle longitudinal axis, by at least 48millimeters.
 25. The all-terrain vehicle of claim 24, wherein the tirehas an inflated outer diameter of at least about 660 millimeters. 26.The all-terrain vehicle of claim 24, further comprising right and leftlower control arms, each lower control arm having an inner pivotcoupling operably coupled to the frame and an outer pivot couplingoperably coupled to one of the front wheels, each lower control armhaving a control arm length between the inner pivot coupling and theouter pivot coupling, the sum of the control arm lengths of the rightand left lower control arms defining a combined control arm length; andwherein the ratio of the combined control arm length to the track widthis at least about 0.84.
 27. The all-terrain vehicle of claim 26, whereineach of the control arms is angled from horizontal by less than about 30degrees.
 28. The all-terrain vehicle of claim 24, wherein: each frontwheel rotates about a rotational axis; and the king pin axis is offsetfrom the front wheel axis, measured along the rotational axis, by lessthan 30 millimeters.
 29. The all-terrain vehicle of claim 24, furthercomprising: a brake disc received within the wheel; a control armsupported by the frame; a spindle connected to the control arm by thepivot coupling; a hub rotatably supported by the spindle; a fastenerextending through the brake disc, the hub, and the wheel; and a securingmember connecting with the fastener to operably couple the brake disk,the hub, and the wheel.
 30. The all-terrain vehicle of claim 29, furthercomprising a brake caliper supported within the wheel and configured tofrictionally engage the brake disc.